Board: make string formatting stuff const

Cargo.lock

@@ -145,6 +145,12 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "const-str"
+version = "0.6.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9e991226a70654b49d34de5ed064885f0bef0348a8e70018b8ff1ac80aa984a2"
+
 [[package]]
 name = "const_for"
 version = "0.1.5"
@@ -449,6 +455,7 @@ dependencies = [
  "allocative",
  "arrayvec",
  "console",
+ "const-str",
  "const_for",
  "criterion",
  "crossbeam-channel",

Cargo.toml

@@ -25,6 +25,7 @@ debug = true
 allocative = "0.3"
 arrayvec = "0.7"
 console = "0.15"
+const-str = "0.6"
 const_for = "0.1"
 crossbeam-channel = "0.5"
 either = "1.13"

src/repr/board.rs

@@ -88,22 +88,22 @@ pub struct Board {
 impl fmt::Display for Board {
     #[allow(clippy::repeat_once)] // clippy gets mad about when PADDING == 1
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        let horiz_sep_line = "-".repeat((Self::SIZE * 2 + 1) as usize);
+        const HORIZ_SEP_LINE: &str = const_str::repeat!("-", (Board::SIZE * 2 + 1) as usize);
 
         // basically calculates the # of digits BOARD_SIZE needs
         const PADDING: usize = (Board::SIZE - 1).ilog10() as usize + 1;
 
-        let space_padding = " ".repeat(PADDING);
+        const SPACE_PADDING: &str = const_str::repeat!(" ", PADDING);
 
         // Print numbers at top so the board can be read more easier
-        write!(f, "{} ", space_padding)?;
+        write!(f, "{} ", SPACE_PADDING)?;
         for j in (0..Self::SIZE).rev() {
             write!(f, "{:0PADDING$} ", j)?;
         }
         writeln!(f)?;
 
         for i in (0..Self::SIZE).rev() {
-            writeln!(f, "{}{}", space_padding, horiz_sep_line)?;
+            writeln!(f, "{}{}", SPACE_PADDING, HORIZ_SEP_LINE)?;
 
             write!(f, "{:0PADDING$}|", i)?;
             for j in (0..Self::SIZE).rev() {
@@ -120,7 +120,7 @@ impl fmt::Display for Board {
         }
 
         // put a line at the bottom of the board too
-        writeln!(f, " {}", horiz_sep_line)?;
+        writeln!(f, " {}", HORIZ_SEP_LINE)?;
 
         // Print the current score
         write!(